HIV continues to pose a significant public health concern, and recent estimates have indicated a substantial increase in new HIV infections among North American men who have sex with men (MSM), mainly resulting from continued unprotected sexual activity. Although alcohol consumption has been implicated as a factor in unprotected sex and subsequent HIV transmission, no research to date has assessed the causal role of alcohol in risky sex among HIV-positive populations. The specific aims of the present investigation therefore focus on 1) assessing the causal impact of acute alcohol consumption on intentions to engage in unprotected sex among HIV-positive MSM, and exploring the interactions among acute alcohol consumption, sexual arousal, and risk-relevant partner factors on the sexual decision making process; and 2) assessing the moderating role of risky personality traits and alcohol expectancies on the causal relationship between acute alcohol consumption and HIV-positive MSM's risky sex intentions. This investigation will involve an innovative experimental approach in which 130 HIV-positive MSM will undergo an alcohol manipulation (control/placebo/alcohol: target BAC=0.08%), watch brief video clips as part of a sexual arousal induction (no arousal/sexual arousal), and indicate their intentions to engage in a range of protected and unprotected sexual acts with 18 hypothetical sexual partners who differ in terms of risk-relevant characteristics (i.e., HIV serostatus, physical attractiveness, relationship type, and preference for condom use). Prior to experimental procedures, measures of sexual sensation seeking, sexual compulsivity, and sex-related alcohol expectancies will also be administered. It is hypothesized that acute alcohol consumption (H1) and sexual arousal (H2) will cause HIV-positive MSM to indicate stronger intentions to engage in unprotected sex, and over and above the impact of the main effects for these two factors, risk intentions will be strongest for HIV-positive MSM who have received both alcohol and the sexual arousal induction (H3). Higher order interactions among acute alcohol consumption, sexual arousal, and partner-related factors will be explored (H4), as will the moderating roles of sexual sensation seeking, sexual compulsivity (H5), and alcohol-related expectancies (H6) on the alcohol-risky sex relationship. Results from this investigation may have an impact not only on the development of interventions that specifically target sexual risk behavior among HIV-positive individuals, but also on alcohol- related interventions that could potentially work in concert with HIV risk-reduction initiatives. PUBLIC HEALTH RELEVANCE: This investigation will consist of an experiment involving HIV-positive gay and bisexual men to assess whether consuming alcohol increases their intentions to have sex without condoms. Given the recent increases in new HIV infections among gay and bisexual men, results from this study will have a significant impact on public health, in that the knowledge to be gained will help guide the development of safer sex promotion programs and alcohol interventions that can be used together to help HIV-positive individuals stay safe, which should reduce the chances of HIV being transmitted to non-infected others.